Events leading to meiosis and sporulation of the yeast Saccharomyces cerevisiae are being studied to understand the control of a gametogenic process. Sporulation only occurs in diploid strains heterozygous (a/alpha for mating type alleles. We are attempting to isolate mutants temperature-sensitive for the mating type alleles which could be used to study the times prior to and during sporulation during which the mating type locus exerts its effect. A second major focus involves the control of RNA synthesis during sporulation, especially those events are sporulation-specific. This study includes alterations in robosomal RNA synthesis and processing as well as changes in messenger RNA.